What is the total EXTRA lift produced using an 80 deg flap? ( 50 deg flap at 30 deg AOA ) and distributed propulsion.
Specs: Ultralight, stall speed 20mph, ROW of 12 x 15" props along entire wing span in DISTRIBUTED PROPULSION, max local AOA estimated at < 9 deg ), electric 25 hp (total), MTOW 500 lbs, low wing in ground effect, max 3 ft height for xSTOL/nVTOL, VG's, full span single slotted flaps with spoilers , Clmax: 3.4.
A low wing ultralight accelerates with a short field takeoff, along a runway to 20mph and rotates to 30 deg AoA just prior to takeoff, producing the following:
Total lift = Wing lift (bernoulli/momentum/vortex lift + deflection lift ) + Prop lift + Flap Lift
- Wing lift:
standard wing lift formulas, lift equal to airplane weight of 500 lbs.
- Prop lift:
Estimated thrust at 20mph: 5lbs/Hp thrust x 25 HP = 125lbs thrust.
Prop lift = 125 lbs x sin ( radians(30 deg))= 62 lbs
- 80 deg Flap Lift
Thrust due to Prop wash on bottom of wing hitting flap = 30%(???) of total thrust = 37 lbs.
- Total extra vertical thrust/lift
= 62 + 37 = approx 100 lbs ( 20% extra vertical thrust/lift...!!!! )
- Reduced MTOW wing requirements at Vtakeoff to Vflap
orginal MTOW = 500 lbs.
MTOW revised= MTOW original - extra vertical lift = 500lbs - 100 lbs.= 400 lbs.
This is the reason for asking the question:
Could I then resize my wings based on 400 lbs MTOW at Vtakeoff(Vso) to Vf, not 500 lbs?
Is this correct thinking?
See black tuft dwg below showing downwards air flow.